Abstract

Introduction: Labour pain is one of the most severe types of pain ever to be experienced. Entonox is a nitrous oxide (N2O), a self administered patient controlled inhalational analgesia. Our research is focused to study about this aspect of Entonox that is reduction in the duration of labour by making cervical dilatation faster. The aims and objectives of our study was to determine the effect of entonox on duration of first stage of labour and to determine the effect of entonox on rate of cervical dilatation.

Methodology: A prospective observational study was carried out Pushpagiri Institute of Medical Sciences and Research Centre in Kerala, India, for a period of 6 months consecutive sampling: sample size obtained is 20 per group, grouped them into two groups depending upon the analgesic of choice. The study tool was a Performa and variables entered into Microsoft excel spreadsheet and analysed SPSS 18.0 software package. Results presented as frequency and percentages for categorical data and descriptive statistics for continuous data. The duration of labour was presented as mean and SD and cervical dilatation rate is calculated as cm in dilatation divided by duration of first stage and this also was presented as mean and SD. These two outcome variables was compared between entonox and control Mann-Whitney U Test.

Results: There was 20 study participants each in the two groups. 10 primigravidas and 10 multigravidas, with mean age was 28.15 ± 2.66 years and majority of them belong to normal BMI. Although there was no difference with respect to the cervical dilatation at the onset of usage of Entonox, it was observed that there was significant reduction in the duration of labour and usage of Entonox as there was a increase in cervical dilatation rate when compared to women who chose other analgesics. All these factors also found to be statistically significant.

Conclusion: A part from analgesic effect nitrous oxide also is shown to decrease the duration of active phase of labour by making cervical dilatation faster and lowering the duration of usage of labour analgesics, which makes labour a pleasant experience for woman.

• 1.   Najafian M, Cheraghi M, Pourmehdi Z, Nejad AD. The effect of nitrous oxide (Entonox) on labour pain relief during delivery stages. Int J Pharm Ther. 2013;4:242–6.
• 2.   Kranke P, Giard T, Lavandhomme P, Melber A, Jokinen J, Mellenbach RM, et al. Must we press on until a young mother dies? Remifentanil patient controlled analgesia in labour may not be suited as a “poor man’s epidural”. BMC Pregnancy Childbirth. 2013;13:139.
• 3.   Cunningham F, Leveno K, Bloom S, Spong C, Dashe J, Hoffman B, Casey B, Sheffield J. Williams Obstetrics. 24th ed. New York: McGraw Hill Education; 2014. p. 25, 504.
• 4.   Parsa P, Saeedzadeh N. The Effect of Entonox on Labour Pain Relief among Nulliparous Women: A Randomized Controlled Trial. J Clin Diagn Res. 2017 Mar;11(3):QC08–QC11.
• 5.   Collins MR, Starr SA, Bishop JT, Baysinger CL. Nitrous oxide for labor analgesia: expanding analgesic options for women in United States. Rev Obstet Gynecol. 2012;5(3–4):e126–31.
• 6.   Pain relief in childbirth [Internet]. [place unknown]: Entonox; [cited 2025 Dec 3].
• 7.   King TL, Wong CA. Nitrous oxide for labor pain: is it a laughing matter? Anesth Analg. 2014;118(1):12–4.
• 8.   Kumar A, Kalra S, Unnikrishnan AG. Metabolic state of the nation: Results of the national family... (Note: Reference 8 appears incomplete in the original list and only the authors and the start of the title were provided. It is formatted as is, assuming it is a journal article.)
• 9.   Naddoni DB, Balakundi SK, Assainar KK. The effect of nitrous oxide (entonox) on labour. Int J Reprod Contracept Obstet Gynecol. 2016;5:835–9.
• 10.   Tazarjani FZ, Sekhavat L, Mibodi MAK. The effect of continuous entonox inhalation on the length of labor in duration of active phase of labor. J Babol Univ Med Sci. 2010;11(6):21–5.

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